Nasal Cytology Produces Comparable Results to Surgery in CRSwNP

Nasal cytology had proven reliability for biomarker identification of type 2 inflammation in patients who have chronic rhinosinusitis with nasal polyps (CRSwNP), according to new study findings published in The World Allergy Organization Journal.

This potential new method of endotypization, beyond systemic and histological biomarkers currently used for endotypization, would be used to facilitate patient selection for biological drug utilization, noted the authors. They evaluated the method using samples from the inferior nasal turbinate and polypoid tissue; surgical polyp tissue was also collected and compared with the nasal cytology samples.

There were 33 consecutive patients with CRSwNP included (mean [SD] age, 49.9 [13/3] years; 15.2% smokers; female patients, 42.2%); all were scheduled for functional endoscopic sinus surgery between June 2020 and 2021 at the Personalized Medicine, Asthma and Allergy, Humanitas Clinical and Research Hospital in Rozzano, Milan, Italy.

“Suggested type 2 inflammatory biomarkers include and local but invasive methods,” the authors wrote. “It would be desirable to be able to use a noninvasive local biomarker, possibly inexpensive, and whose results can be obtained in a short time.”

Among the patient population, 39.4% were considered atopic, 51.5% had asthma, and 21.2% had nonsteroidal anti-inflammatory drugs exacerbated respiratory disease. Mean measures for Nasal Polyp Score (NPS), blood eosinophil count, and neutrophil count were 6.1 (1.8), 410.0 (352.7) cells/mcL, and 4086.2 (1598.6) cells/mcL, respectively.

When findings from the 3 sampling methods were compared, the researchers saw the following results:

• Eosinophil counts:
  • Nasal polyp tissue: 43.7 (39.6) cells/HPF
  • Nasal polyps cytology: 32.8 (44.7) cells/HPF
  • Inferior turbinate cytology: 27.6 (58.0) cells/HPF
• Neutrophil counts:
  • Nasal polyp tissue: 24.4 (45.5) cells/HPF
  • Nasal polyps cytology: 30.0 (58.0) cells/HPF
  • Inferior turbinate cytology: 26.1 (54.8) cells/HPF

Among the 84.8% patients who were shown to have type-2 high CRSwNP (at least 10 tissue eosinophils/HPF), the age trended younger (47.8 [13.2] vs 61.6 [5.0] years) and they had a lower NPS (5.9 vs 7.2) compared with the patients classified as type-2 low CRSwNP. However, patients with type-2 high CRSwNP had significantly higher nasal polyps cytology eosinophils (5.2.5 [67.0] vs 12.2 [17.3] cells/HPF) and mean inferior turbinate cytology eosinophils (32.0 [62.1] vs 2.9 [2.9]).

Overall, the study investigators determined, the cytological samples’ eosinophil count from scraping on the nasal polyps was comparable to the count they got from the surgical samples but nasal turbinate results were inferior to the tissue samples. In addition, Bland-Altman plots showed concordance between nasal polyp cytology-derived eosinophil count and histological data.

The significant differences seen between these 2 measures for especially high eosinophil counts was attributed to “the fact that cytology is able to evaluate the presence of cells detached from the polypoid tissue through the scraping maneuver which, in cases of extremely relevant eosinophilic tissue infiltrates, could partially underestimate the level of inflammation, while clearly highlighting the type 2 inflammatory nature of the nasal polyp,” the authors wrote.

“Nasal cytology is a simple, rapid, inexpensive, noninvasive, and potentially point-of-care diagnostic method,” they concluded. “Our results add a further modality of use of nasal cytology, demonstrating that it provides results comparable to those obtained from the much more invasive collection of surgical biopsy samples.”

They added that their findings are especially relevant in the context of precision medicine, because they can add to criteria used to identify patients with inflammatory endotype treatable disease who may be eligible for treatment with biologics, making nasal cytology “a new and reliable biomarker of type 2 inflammatory involvement in patients with CRSwNP.”

Reference

Paoletti G, Malvezzi L, Riccio AM, et al. Nasal cytology as a reliable non-invasive procedure to phenotype patients with type 2 chronic rhinosinusitis with nasal polyps. World Allergy Organ J. Published online October 18, 2022. doi:10.1016/j.waojou.2022.100700